Thursday, June 25, 2009

Linux on Two Imacs


My sister, Kristina, has a summer job teaching at a local daycare. Her classroom had two imacs in it that still ran OS 9, but unfortunately, one of the kids had set passwords on them, then left or forgotten it, so there was no way to use them any more. All Kristina wanted was something with a word processor, and maybe some games. Sounds like a perfect fit for Linux if I've ever heard one.

Hardware:
So hardware wise, what have we got to work with? One graphite and one blue 3G Imac, which had 10 / 13 GB hard drives, and 128 / 192 MB RAM. That is a little tight, but still definitely useful if you're careful about how you set it up. Once running, I was able to browse reddit and check my email on them no problem.

Software:
Of course, the CD drives didn't work, so I got more practice netboot installing PPC Ubuntu. One of them wouldn't get the boot filename from my DHCP server, so I had to pass that to it in openfirmware (boot enet:0,yaboot instead of boot enet:0). I partitioned the systems 5GB XFS for root, and the rest for home, also XFS. I used XFS because, like most PPC hardware, the clock batteries are dead in these systems, so when the power dies and the clocks reset to 1903, I don't want the FS to sit there and fsck because it was last mounted in the future. Considering how lightly these systems are going to be used, it doesn't really matter how fast the file system actually performs, as much as how quickly it boots when the kid sits down. Didn't feel fancy enough to setup NFS between them, though in a more serious installation, that could be an option to have saved files available on both.

128 MB of RAM is too little to run GNOME, so I only installed a command line system and built a GUI from the ground up. For some reason, the Imacs were only displaying 16 colors, so slim looked awful, and auto-login wasn't working anyways, so I switched slim out for xdm, which looks fine (grey FTW). This means that the students have to type in the username and password (both creatively set to student), but that's not a big deal. I created a teacher account during the install process, then adduser'ed the student account so it wouldn't be a sudoer, and now will be even harder to do any real damage with (just being Unix based by itself helps make it damage resistant, they'd have to know what to type in!).

On top of xdm, I installed xfce4. I looked at using some of the ridiculously light window managers, like fluxbox, etc, but felt that they were just a little too foreign for children in a classroom. I've also never liked Xubuntu; it always seems like it tries to do everything Ubuntu can, so it's not *that* much lighter than Ubuntu proper. I figure that if I can run Xubuntu on a system, I may as well just go with Ubuntu, be loads more comfortable with the same wm I use on everything else, and deal with a little more slowness. Xubuntu would also be rather overkill for what I need, so xfce4 proper it is.

At this point, I had an entirely working GUI, with absolutely no programs in it. Beyond some simple utilities like a calculator and a picture viewer, I installed three major programs. Abiword, along with all the plugins (why not?) as a functional, yet light, word processor. For games, I installed gnome-games, which seemed to work surprisingly well on 400MHz systems, and here is the real gold mine, sgt-puzzles. They lack some polish, and it's not always entirely clear what you're meant to do, but it's a huge number of small, quick puzzle games, perfect for a classroom.

The whole setup took about two to three days, and after setting them back up, the students have been using them all week with no problems I've heard about. One boy told my sister he was very happy with the new computers, because they old ones only had one game on them, but now they have a million! I appreciated that.

Here is a final list of everything I installed on top of a cli system.
  • xdm - desktop manager / login screen
  • xfce4 - window manager. I enjoy the mouse icon as well.
  • gnome-icon-theme - seemed some icons were missing from xfce4 by itself
  • firefox - Websites look really bad in 16 color, but if these ever happen to be plugged into a network, they would be very usable browsing machines.
  • ristretto - picture viewer
  • mousepad - simple text editor
  • galculator - basic calculator program
  • gnome-games
  • sgt-puzzles
  • abiword abiword-help abiword-plugins - word processor
  • gnumeric - spreadsheet program, in case one is ever needed
Anything else you think would be perfect to have on old slow machines sitting in a classroom? Please write in the comments.

San Jose Bike Party

Kristina and I got invited to the San Jose Bike Party last Friday evening. It's this crazy event where literally 1,500 bikers met in a parking lot, then rode 17 miles across town, taking the road by shear numbers. We rode on her tandem, which worked great until it lost a spacer a mile from the end, so we had to walk it the rest of the way.

The experience was generally positive, but there was some funkiness that has started creeping into the community. People were running red lights, then running from the police when they get lit up for it. There were bystanders throwing rocks and eggs at us, which was super unfortunate, but considering how big this event is, it'd be incredible if this type thing didn't happen. We had a good time.

Wednesday, June 17, 2009

Verizon Wireless Network Extender

I been home from Davis for almost two days now, and it's probably been the busiest two days I can think of. My dad has made listing projects he wants me to work on almost an art form. Lucky for you, that means I'm going to actually have some real content now.

Most exciting project so far is this black router-like device from Verizon. It's called a Femtocell, and it is pretty much a miniature cell phone tower that you plug into your internet connection, and promptly have five bars throughout your entire house. Granted, it cost $270, which is a little outrageous considering that we are now using OUR electricity, and OUR internet connection, to extent Verizon's network, because they couldn't get their act together and get decent coverage (read: any coverage at all) to our house. At the same time though, unlike many other companies, they aren't going to charge us $10 a month to use our power and our internet to help make their network more appealing, to us, so we would want to give them more of our money, which makes me SICK.

Anyways, onto this specific product. In a word, it works. Getting it working was litterally a 20 minute excercise in plugging in cables and waiting for the GPS to pick up.

To operate, it needs three things: Power, internet, and GPS coverage. The GPS is for the E911 service so when someone is laying in your driveway, and wasn't smart enough to program the local 7 digit emergncy number into their Verizon cell phone, the police will still know where they are, which is very clever. Unfortunately, when the instructions say that you need to put this thing near a window to get GPS service, they're really not being that conservative. It really doesn't work anywhere else. Except, that they're also clever enough to include ~25 feet of coax to allow you to run the GPS antenna (which pops out of the device and who's shape is reminiscent of a USB dongle) out to aa window, so I currently have it running in the dead center of my house with all LEDs blue.

The one oddity about it is the bandwidth usage. In different places in the documentation it says it needs 300kbps (37.5kBps), or 40kbps (5kBps). The 300 number caused me some concern, since our internet definitely doesn't get 300kbps up, so if it meant 300 up and down, we were screwed. Luckily, I haven't seen anything even close to 300kbps in either direction, so I have no idea where that number is coming from. The femtocell has 3 standard channels + 1 E911 channel, and from playing with it and watching my router, a single phone call looks to take 6-7kBps in bother directions. Standby bandwidth usage looks to be a 10kB download every 60 seconds, and maybe 3kB up scattered throughout the minute. Pretty much negliable.

It definitely suffers from heavy bandwidth usage, such as bittorrent. I haven't gotten around to playing with the QoS settings on our router yet, but as would be expected, bulk traffic and real time traffic just don't mix, end of story.

Would I say that this thing is worth the $270 we spent on it? Probably not. Is it worth something remotely close to $270? Definitely! I can sit anywhere in my house and make and receive phone calls, crystall clear (though possible with slightly more lag? Possible just me looking for it). Does it mean our neighboors are freeloading off our femtocell? Possible. I was picked up on it instead of the towers anywhere in our house. I would no be surprised if our immediate neighboors might pick up on it if they happen to be Verizon, but luckily we can set it to give our numbers priority. We still need to do some more range testing for it.

UPDATE: After some experimenting, it looks like cells would only *connect* to it from the near half of only one of our neighbors properties. The range of the device was somewhat farther than that, but that was only when the call started closer and then moved away. Note that any call started on a tower will never transfer to the femtocell, possible to prevent passer-bys from randomly connecting to it, only to go out of range again in seconds.

Monday, June 1, 2009

Link Dump

Interesting links from the last month:
Father takes three children and three clocks on vacation. Of course, they were Cesium clocks, so at the end of the weekend, he was able to test his calculations for the time dilation of being on the top of a mountain for 40 hours. They gained 23ns for being farther out of the Earth's gravity well.
Endurance Hunting. The evolutionary advantage of sweat glands never made sense until I read an article about this. Wildlife may be able to run faster than humans, but we can chase them to exhaustion.
Epic prank video.
Apple keeps screwing itself with this iPhone market.
Sleeping pigs.
Star what?
Vaseline on a birdfeeder.
Interesting article on how not to baby your children.